Indication of globally synchronous communications mode

ABSTRACT

Indication of globally synchronous communications mode is disclosed. A first node may detect an indication signal transmitted by a second node at a synchronization boundary of a shared communication channel. The indication signal is configured to identify a first transmission synchronization mode of the second node. The first node may then adjust its communications configuration in response to the indication signal. In making such adjustments, the first node may either contend for communications on the shared communication channel using the first transmission synchronization mode or refrain from attempting the communications on the shared communication channel using a second transmission synchronization mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/955,591, entitled, “INDICATION OF GLOBALLYSYNCHRONOUS COMMUNICATIONS MODE,” filed on Dec. 31, 2019, which isexpressly incorporated by reference herein in its entirety.

BACKGROUND Field

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to indication of globallysynchronous communications mode.

Background

Wireless communication networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, and the like. These wireless networks may be multiple-accessnetworks capable of supporting multiple users by sharing the availablenetwork resources. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources. One example of such a network is theUniversal Terrestrial Radio Access Network (UTRAN). The UTRAN is theradio access network (RAN) defined as a part of the Universal MobileTelecommunications System (UMTS), a third generation (3G) mobile phonetechnology supported by the 3rd Generation Partnership Project (3GPP).Examples of multiple-access network formats include Code DivisionMultiple Access (CDMA) networks, Time Division Multiple Access (TDMA)networks, Frequency Division Multiple Access (FDMA) networks, OrthogonalFDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stationsor node Bs that can support communication for a number of userequipments (UEs). A UE may communicate with a base station via downlinkand uplink. The downlink (or forward link) refers to the communicationlink from the base station to the UE, and the uplink (or reverse link)refers to the communication link from the UE to the base station.

A base station may transmit data and control information on the downlinkto a UE and/or may receive data and control information on the uplinkfrom the UE. On the downlink, a transmission from the base station mayencounter interference due to transmissions from neighbor base stationsor from other wireless radio frequency (RF) transmitters. On the uplink,a transmission from the UE may encounter interference from uplinktransmissions of other UEs communicating with the neighbor base stationsor from other wireless RF transmitters. This interference may degradeperformance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, thepossibilities of interference and congested networks grows with more UEsaccessing the long-range wireless communication networks and moreshort-range wireless systems being deployed in communities. Research anddevelopment continue to advance wireless technologies not only to meetthe growing demand for mobile broadband access, but to advance andenhance the user experience with mobile communications.

SUMMARY

In one aspect of the disclosure, a method of wireless communicationincludes detecting, by a first node, an indication signal transmitted bya second node at a synchronization boundary of a shared communicationchannel, wherein the indication signal identifies a first transmissionsynchronization mode of the second node, and adjusting, by the firstnode, a communications configuration for the shared communicationchannel in response to detection of the indication signal, wherein anadjustment to the communications configuration includes eithercontending, by the first node, for communications on the sharedcommunication channel using the first transmission synchronization modeor refraining, by the first node, from attempting the communications onthe shared communication channel using a second transmissionsynchronization mode.

In an additional aspect of the disclosure, a method of wirelesscommunication includes contending, by a first node, for access to ashared communication spectrum with a listen before talk (LBT) procedureat a synchronization boundary, transmitting, by the first node,according to a first synchronization mode, data in a channel occupationtime (COT) established in response to success of the LBT procedure, andtransmitting, by the first node, an indication signal after an end ofthe COT at a subsequent synchronization boundary, wherein the indicationsignal identifies the first synchronization mode.

In an additional aspect of the disclosure, an apparatus configured forwireless communication includes means for detecting, by a first node, anindication signal transmitted by a second node at a synchronizationboundary of a shared communication channel, wherein the indicationsignal identifies a first transmission synchronization mode of thesecond node, and means for adjusting, by the first node, acommunications configuration for the shared communication channel inresponse to detection of the indication signal, wherein an adjustment tothe communications configuration includes either means for contending,by the first node, for communications on the shared communicationchannel using the first transmission synchronization mode or means forrefraining, by the first node, from attempting the communications on theshared communication channel using a second transmission synchronizationmode.

In an additional aspect of the disclosure, an apparatus configured forwireless communication includes means for contending, by a first node,for access to a shared communication spectrum with an LBT procedure at asynchronization boundary, means for transmitting, by the first node,according to a first synchronization mode, data in a COT established inresponse to success of the LBT procedure, and means for transmitting, bythe first node, an indication signal after an end of the COT at asubsequent synchronization boundary, wherein the indication signalidentifies the first synchronization mode.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon. Theprogram code further includes code to detect, by a first node, anindication signal transmitted by a second node at a synchronizationboundary of a shared communication channel, wherein the indicationsignal identifies a first transmission synchronization mode of thesecond node, and code to adjust, by the first node, a communicationsconfiguration for the shared communication channel in response todetection of the indication signal, wherein an adjustment to thecommunications configuration includes either code to contend, by thefirst node, for communications on the shared communication channel usingthe first transmission synchronization mode or code to refrain, by thefirst node, from attempting the communications on the sharedcommunication channel using a second transmission synchronization mode.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon. Theprogram code further includes code to contend, by a first node, foraccess to a shared communication spectrum with an LBT procedure at asynchronization boundary, code to transmit, by the first node, accordingto a first synchronization mode, data in a COT established in responseto success of the LBT procedure, and code to transmit, by the firstnode, an indication signal after an end of the COT at a subsequentsynchronization boundary, wherein the indication signal identifies thefirst synchronization mode.

In an additional aspect of the disclosure, an apparatus configured forwireless communication is disclosed. The apparatus includes at least oneprocessor, and a memory coupled to the processor. The processor isconfigured to detect, by a first node, an indication signal transmittedby a second node at a synchronization boundary of a shared communicationchannel, wherein the indication signal identifies a first transmissionsynchronization mode of the second node, and to adjust, by the firstnode, a communications configuration for the shared communicationchannel in response to detection of the indication signal, wherein anadjustment to the communications configuration includes eitherconfiguration of the at least one processor to contend, by the firstnode, for communications on the shared communication channel using thefirst transmission synchronization mode or to refrain, by the firstnode, from attempting the communications on the shared communicationchannel using a second transmission synchronization mode.

In an additional aspect of the disclosure, an apparatus configured forwireless communication is disclosed. The apparatus includes at least oneprocessor, and a memory coupled to the processor. The processor isconfigured to contend, by a first node, for access to a sharedcommunication spectrum with an LBT procedure at a synchronizationboundary, to transmit, by the first node, according to a firstsynchronization mode, data in a COT established in response to successof the LBT procedure, and to transmit, by the first node, an indicationsignal after an end of the COT at a subsequent synchronization boundary,wherein the indication signal identifies the first synchronization mode.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purpose ofillustration and description, and not as a definition of the limits ofthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wirelesscommunication system.

FIG. 2 is a block diagram illustrating a design of a base station and aUE configured according to one aspect of the present disclosure.

FIG. 3 is a block diagram illustrating a portion of a NR-U networkconfigured to support synchronous communication mode within a sharedcommunication spectrum.

FIGS. 4A and 4B are block diagrams illustrating example blocks executedto implement aspects of the present disclosure.

FIGS. 5A and 5B are block diagrams illustrating portions of a NR-Unetwork having nodes serving UEs, in which all such nodes are configuredfor indicating synchronous communications according to aspects of thepresent disclosure.

FIG. 6 is a block diagram illustrating a base station configuredaccording to one aspect of the present disclosure.

FIG. 7 is a block diagram illustrating a UE configured according to oneaspect of the present disclosure.

The Appendix provides further details regarding various embodiments ofthis disclosure and the subject matter therein forms a part of thespecification of this application.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings and appendix, is intended as a description of variousconfigurations and is not intended to limit the scope of the disclosure.Rather, the detailed description includes specific details for thepurpose of providing a thorough understanding of the inventive subjectmatter. It will be apparent to those skilled in the art that thesespecific details are not required in every case and that, in someinstances, well-known structures and components are shown in blockdiagram form for clarity of presentation.

This disclosure relates generally to providing or participating inauthorized shared access between two or more wireless communicationssystems, also referred to as wireless communications networks. Invarious embodiments, the techniques and apparatus may be used forwireless communication networks such as code division multiple access(CDMA) networks, time division multiple access (TDMA) networks,frequency division multiple access (FDMA) networks, orthogonal FDMA(OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks,GSM networks, 5^(th) Generation (5G) or new radio (NR) networks, as wellas other communications networks. As described herein, the terms“networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and thelike. UTRA, E-UTRA, and Global System for Mobile Communications (GSM)are part of universal mobile telecommunication system (UMTS). Inparticular, long term evolution (LTE) is a release of UMTS that usesE-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documentsprovided from an organization named “3rd Generation Partnership Project”(3GPP), and cdma2000 is described in documents from an organizationnamed “3rd Generation Partnership Project 2” (3GPP2). These variousradio technologies and standards are known or are being developed. Forexample, the 3rd Generation Partnership Project (3GPP) is acollaboration between groups of telecommunications associations thataims to define a globally applicable third generation (3G) mobile phonespecification. 3GPP long term evolution (LTE) is a 3GPP project whichwas aimed at improving the universal mobile telecommunications system(UMTS) mobile phone standard. The 3GPP may define specifications for thenext generation of mobile networks, mobile systems, and mobile devices.The present disclosure is concerned with the evolution of wirelesstechnologies from LTE, 4G, 5G, NR, and beyond with shared access towireless spectrum between networks using a collection of new anddifferent radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diversespectrum, and diverse services and devices that may be implemented usingan OFDM-based unified, air interface. In order to achieve these goals,further enhancements to LTE and LTE-A are considered in addition todevelopment of the new radio technology for 5G NR networks. The 5G NRwill be capable of scaling to provide coverage (1) to a massive Internetof things (IoTs) with an ultra-high density (e.g., ˜1 M nodes/km²),ultra-low complexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g.,˜10+ years of battery life), and deep coverage with the capability toreach challenging locations; (2) including mission-critical control withstrong security to safeguard sensitive personal, financial, orclassified information, ultra-high reliability (e.g., ˜99.9999%reliability), ultra-low latency (e.g., ˜1 ms), and users with wideranges of mobility or lack thereof; and (3) with enhanced mobilebroadband including extreme high capacity (e.g., ˜10 Tbps/km²), extremedata rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates),and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms withscalable numerology and transmission time interval (TTI); having acommon, flexible framework to efficiently multiplex services andfeatures with a dynamic, low-latency time division duplex(TDD)/frequency division duplex (FDD) design; and with advanced wirelesstechnologies, such as massive multiple input, multiple output (MIMO),robust millimeter wave (mmWave) transmissions, advanced channel coding,and device-centric mobility. Scalability of the numerology in 5G NR,with scaling of subcarrier spacing, may efficiently address operatingdiverse services across diverse spectrum and diverse deployments. Forexample, in various outdoor and macro coverage deployments of less than3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz,for example over 1, 5, 10, 20 MHz, and the like bandwidth. For othervarious outdoor and small cell coverage deployments of TDD greater than3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHzbandwidth. For other various indoor wideband implementations, using aTDD over the unlicensed portion of the 5 GHz band, the subcarrierspacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, forvarious deployments transmitting with mmWave components at a TDD of 28GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of the 5 G NR facilitates scalable TTI fordiverse latency and quality of service (QoS) requirements. For example,shorter TTI may be used for low latency and high reliability, whilelonger TTI may be used for higher spectral efficiency. The efficientmultiplexing of long and short TTIs to allow transmissions to start onsymbol boundaries. 5 G NR also contemplates a self-contained integratedsubframe design with uplink/downlink scheduling information, data, andacknowledgement in the same subframe. The self-contained integratedsubframe supports communications in unlicensed or contention-basedshared spectrum, adaptive uplink/downlink that may be flexiblyconfigured on a per-cell basis to dynamically switch between uplink anddownlink to meet the current traffic needs.

Various other aspects and features of the disclosure are furtherdescribed below. It should be apparent that the teachings herein may beembodied in a wide variety of forms and that any specific structure,function, or both being disclosed herein is merely representative andnot limiting. Based on the teachings herein one of an ordinary level ofskill in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,a method may be implemented as part of a system, device, apparatus,and/or as instructions stored on a computer readable medium forexecution on a processor or computer. Furthermore, an aspect maycomprise at least one element of a claim.

FIG. 1 is a block diagram illustrating an example of a wirelesscommunications system 100 that supports appending a unique pattern(e.g., on/off pattern) following a synchronous mode transmission thatends at a synchronization boundary. The pattern may begin with a single“off” slot that would ensure that synchronization mode detection is notimpacted and a listen before talk (LBT) countdown is not triggered.Other neighboring nodes, in detecting the unique pattern, would knowthat the current communications are using a synchronous modetransmission (e.g., global vs. local synchronization mode) in accordancewith aspects of the present disclosure. The wireless communicationssystem 100 includes base stations 105, UEs 115, and a core network 130.In some examples, the wireless communications system 100 may be a LongTerm Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-APro network, or NR network. In some cases, wireless communicationssystem 100 may support enhanced broadband communications, ultra-reliable(e.g., mission critical) communications, low latency communications, orcommunications with low-cost and low-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Base stations 105 described herein mayinclude or may be referred to by those skilled in the art as a basetransceiver station, a radio base station, an access point, a radiotransceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB orgiga-NodeB (either of which may be referred to as a gNB), a Home NodeB,a Home eNodeB, or some other suitable terminology. Wirelesscommunications system 100 may include base stations 105 of differenttypes (e.g., macro or small cell base stations). The UEs 115 describedherein may be able to communicate with various types of base stations105 and network equipment including macro eNBs, small cell eNBs, gNBs,relay base stations, and the like.

Each base station 105 may be associated with a particular geographiccoverage area 110 in which communications with various UEs 115 issupported. Each base station 105 may provide communication coverage fora respective geographic coverage area 110 via communication links 125,and communication links 125 between a base station 105 and a UE 115 mayutilize one or more carriers. Communication links 125 shown in wirelesscommunications system 100 may include uplink transmissions from a UE 115to a base station 105, or downlink transmissions from a base station 105to a UE 115. Downlink transmissions may also be referred to as forwardlink transmissions while uplink transmissions may also be referred to asreverse link transmissions.

The geographic coverage area 110 for a base station 105 may be dividedinto sectors making up a portion of the geographic coverage area 110,and each sector may be associated with a cell. For example, each basestation 105 may provide communication coverage for a macro cell, a smallcell, a hot spot, or other types of cells, or various combinationsthereof. In some examples, a base station 105 may be movable and,therefore, provide communication coverage for a moving geographiccoverage area 110. In some examples, different geographic coverage areas110 associated with different technologies may overlap, and overlappinggeographic coverage areas 110 associated with different technologies maybe supported by the same base station 105 or by different base stations105. The wireless communications system 100 may include, for example, aheterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different typesof base stations 105 provide coverage for various geographic coverageareas 110.

The term “cell” refers to a logical communication entity used forcommunication with a base station 105 (e.g., over a carrier), and may beassociated with an identifier for distinguishing neighboring cells(e.g., a physical cell identifier (PCID), a virtual cell identifier(VCID)) operating via the same or a different carrier. In some examples,a carrier may support multiple cells, and different cells may beconfigured according to different protocol types (e.g., machine-typecommunication (MTC), narrowband Internet-of-things (NB-IoT), enhancedmobile broadband (eMBB), or others) that may provide access fordifferent types of devices. In some cases, the term “cell” may refer toa portion of a geographic coverage area 110 (e.g., a sector) over whichthe logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to as a mobile device, a wireless device, a remote device, ahandheld device, or a subscriber device, or some other suitableterminology, where the “device” may also be referred to as a unit, astation, a terminal, or a client. A UE 115 may also be a personalelectronic device such as a cellular phone (UE 115 a), a personaldigital assistant (PDA), a wearable device (UE 115 d), a tabletcomputer, a laptop computer (UE 115 g), or a personal computer. In someexamples, a UE 115 may also refer to a wireless local loop (WLL)station, an Internet-of-things (IoT) device, an Internet-of-everything(IoE) device, an MTC device, or the like, which may be implemented invarious articles such as appliances, vehicles (UE 115 e and UE 115 f),meters (UE 115 b and UE 115 c), or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices, and may provide for automated communication betweenmachines (e.g., via machine-to-machine (M2M) communication). M2Mcommunication or MTC may refer to data communication technologies thatallow devices to communicate with one another or a base station 105without human intervention. In some examples, M2M communication or MTCmay include communications from devices that integrate sensors or metersto measure or capture information and relay that information to acentral server or application program that can make use of theinformation or present the information to humans interacting with theprogram or application. Some UEs 115 may be designed to collectinformation or enable automated behavior of machines. Examples ofapplications for MTC devices include smart metering, inventorymonitoring, water level monitoring, equipment monitoring, healthcaremonitoring, wildlife monitoring, weather and geological eventmonitoring, fleet management and tracking, remote security sensing,physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reducepower consumption, such as half-duplex communications (e.g., a mode thatsupports one-way communication via transmission or reception, but nottransmission and reception simultaneously). In some examples,half-duplex communications may be performed at a reduced peak rate.Other power conservation techniques for UEs 115 include entering a powersaving “deep sleep” mode when not engaging in active communications, oroperating over a limited bandwidth (e.g., according to narrowbandcommunications). In other cases, UEs 115 may be designed to supportcritical functions (e.g., mission critical functions), and a wirelesscommunications system 100 may be configured to provide ultra-reliablecommunications for these functions.

In certain cases, a UE 115 may also be able to communicate directly withother UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device(D2D) protocol). One or more of a group of UEs 115 utilizing D2Dcommunications may be within the geographic coverage area 110 of a basestation 105. Other UEs 115 in such a group may be outside the geographiccoverage area 110 of a base station 105, or be otherwise unable toreceive transmissions from a base station 105. In some cases, groups ofUEs 115 communicating via D2D communications may utilize a one-to-many(1:M) system in which each UE 115 transmits to every other UE 115 in thegroup. In some cases, a base station 105 may facilitate the schedulingof resources for D2D communications. In other cases, D2D communicationsmay be carried out between UEs 115 without the involvement of a basestation 105.

Base stations 105 may communicate with the core network 130 and with oneanother. For example, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., via an S1, N2, N3, orother interface). Base stations 105 may communicate with one anotherover backhaul links 134 (e.g., via an X2, Xn, or other interface) eitherdirectly (e.g., directly between base stations 105) or indirectly (e.g.,via core network 130).

The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. The core network 130 may be anevolved packet core (EPC), which may include at least one mobilitymanagement entity (MME), at least one serving gateway (S-GW), and atleast one packet data network (PDN) gateway (P-GW). The MME may managenon-access stratum (e.g., control plane) functions such as mobility,authentication, and bearer management for UEs 115 served by basestations 105 associated with the EPC. User IP packets may be transferredthrough the S-GW, which itself may be connected to the P-GW. The P-GWmay provide IP address allocation as well as other functions. The P-GWmay be connected to the network operators IP services. The operators IPservices may include access to the Internet, Intranet(s), an IPmultimedia subsystem (IMS), or a packet-switched (PS) streaming service.

At least some of the network devices, such as a base station 105, mayinclude subcomponents such as an access network entity, which may be anexample of an access node controller (ANC). Each access network entitymay communicate with UEs 115 through a number of other access networktransmission entities, which may be referred to as a radio head, a smartradio head, or a transmission/reception point (TRP). In someconfigurations, various functions of each access network entity or basestation 105 may be distributed across various network devices (e.g.,radio heads and access network controllers) or consolidated into asingle network device (e.g., a base station 105).

Wireless communications system 100 may operate using one or morefrequency bands, typically in the range of 300 megahertz (MHz) to 300gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known asthe ultra-high frequency (UHF) region or decimeter band, since thewavelengths range from approximately one decimeter to one meter inlength. UHF waves may be blocked or redirected by buildings andenvironmental features. However, the waves may penetrate structuressufficiently for a macro cell to provide service to UEs 115 locatedindoors. Transmission of UHF waves may be associated with smallerantennas and shorter range (e.g., less than 100 km) compared totransmission using the smaller frequencies and longer waves of the highfrequency (HF) or very high frequency (VHF) portion of the spectrumbelow 300 MHz.

Wireless communications system 100 may also operate in a super highfrequency (SHF) region using frequency bands from 3 GHz to 30 GHz, alsoknown as the centimeter band. The SHF region includes bands such as the5 GHz industrial, scientific, and medical (ISM) bands, which may be usedopportunistically by devices that may be capable of toleratinginterference from other users.

Wireless communications system 100 may also operate in an extremely highfrequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz),also known as the millimeter band. In some examples, wirelesscommunications system 100 may support millimeter wave (mmW)communications between UEs 115 and base stations 105, and EHF antennasof the respective devices may be even smaller and more closely spacedthan UHF antennas. In some cases, this may facilitate use of antennaarrays within a UE 115. However, the propagation of EHF transmissionsmay be subject to even greater atmospheric attenuation and shorter rangethan SHF or UHF transmissions. Techniques disclosed herein may beemployed across transmissions that use one or more different frequencyregions, and designated use of bands across these frequency regions maydiffer by country or regulating body.

Wireless communications system 100 may include operations by differentnetwork operating entities (e.g., network operators), in which eachnetwork operator may share spectrum. In some instances, a networkoperating entity may be configured to use an entirety of a designatedshared spectrum for at least a period of time before another networkoperating entity uses the entirety of the designated shared spectrum fora different period of time. Thus, in order to allow network operatingentities use of the full designated shared spectrum, and in order tomitigate interfering communications between the different networkoperating entities, certain resources (e.g., time) may be partitionedand allocated to the different network operating entities for certaintypes of communication.

For example, a network operating entity may be allocated certain timeresources reserved for exclusive communication by the network operatingentity using the entirety of the shared spectrum. The network operatingentity may also be allocated other time resources where the entity isgiven priority over other network operating entities to communicateusing the shared spectrum. These time resources, prioritized for use bythe network operating entity, may be utilized by other network operatingentities on an opportunistic basis if the prioritized network operatingentity does not utilize the resources. Additional time resources may beallocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resourcesamong different network operating entities may be centrally controlledby a separate entity, autonomously determined by a predefinedarbitration scheme, or dynamically determined based on interactionsbetween wireless nodes of the network operators.

In various implementations, wireless communications system 100 may useboth licensed and unlicensed radio frequency spectrum bands. Forexample, wireless communications system 100 may employ license assistedaccess (LAA), LTE-unlicensed (LTE-U) radio access technology, or NRtechnology in an unlicensed band (NR-U), such as the 5 GHz ISM band. Insome cases, UE 115 and base station 105 of the wireless communicationssystem 100 may operate in a shared radio frequency spectrum band, whichmay include licensed or unlicensed (e.g., contention-based) frequencyspectrum. In an unlicensed frequency portion of the shared radiofrequency spectrum band, UEs 115 or base stations 105 may traditionallyperform a medium-sensing procedure to contend for access to thefrequency spectrum. For example, UE 115 or base station 105 may performa listen before talk (LBT) procedure such as a clear channel assessment(CCA) prior to communicating in order to determine whether the sharedchannel is available.

A CCA may include an energy detection procedure to determine whetherthere are any other active transmissions on the shared channel. Forexample, a device may infer that a change in a received signal strengthindicator (RSSI) of a power meter indicates that a channel is occupied.Specifically, signal power that is concentrated in a certain bandwidthand exceeds a predetermined noise floor may indicate another wirelesstransmitter. A CCA also may include message detection of specificsequences that indicate use of the channel. For example, another devicemay transmit a specific preamble prior to transmitting a data sequence.In some cases, an LBT procedure may include a wireless node adjustingits own backoff window based on the amount of energy detected on achannel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedbackfor its own transmitted packets as a proxy for collisions.

In general, four categories of LBT procedure have been suggested forsensing a shared channel for signals that may indicate the channel isalready occupied. In a first category (CAT 1 LBT), no LBT or CCA isapplied to detect occupancy of the shared channel. A second category(CAT 2 LBT), which may also be referred to as an abbreviated LBT, asingle-shot LBT, or a 25-μs LBT, provides for the node to perform a CCAto detect energy above a predetermined threshold or detect a message orpreamble occupying the shared channel. The CAT 2 LBT performs the CCAwithout using a random back-off operation, which results in itsabbreviated length, relative to the next categories.

A third category (CAT 3 LBT) performs CCA to detect energy or messageson a shared channel, but also uses a random back-off and fixedcontention window. Therefore, when the node initiates the CAT 3 LBT, itperforms a first CCA to detect occupancy of the shared channel. If theshared channel is idle for the duration of the first CCA, the node mayproceed to transmit. However, if the first CCA detects a signaloccupying the shared channel, the node selects a random back-off basedon the fixed contention window size and performs an extended CCA. If theshared channel is detected to be idle during the extended CCA and therandom number has been decremented to 0, then the node may begintransmission on the shared channel. Otherwise, the node decrements therandom number and performs another extended CCA. The node would continueperforming extended CCA until the random number reaches 0. If the randomnumber reaches 0 without any of the extended CCAs detecting channeloccupancy, the node may then transmit on the shared channel. If at anyof the extended CCA, the node detects channel occupancy, the node mayre-select a new random back-off based on the fixed contention windowsize to begin the countdown again.

A fourth category (CAT 4 LBT), which may also be referred to as a fullLBT procedure, performs the CCA with energy or message detection using arandom back-off and variable contention window size. The sequence of CCAdetection proceeds similarly to the process of the CAT 3 LBT, exceptthat the contention window size is variable for the CAT 4 LBT procedure.

Use of a medium-sensing procedure to contend for access to an unlicensedshared spectrum may result in communication inefficiencies. This may beparticularly evident when multiple network operating entities (e.g.,network operators) are attempting to access a shared resource. Inwireless communications system 100, base stations 105 and UEs 115 may beoperated by the same or different network operating entities. In someexamples, an individual base station 105 or UE 115 may be operated bymore than one network operating entity. In other examples, each basestation 105 and UE 115 may be operated by a single network operatingentity. Requiring each base station 105 and UE 115 of different networkoperating entities to contend for shared resources may result inincreased signaling overhead and communication latency.

In some cases, operations in unlicensed bands may be based on a carrieraggregation configuration in conjunction with component carriersoperating in a licensed band (e.g., LAA). Operations in unlicensedspectrum may include downlink transmissions, uplink transmissions,peer-to-peer transmissions, or a combination of these. Duplexing inunlicensed spectrum may be based on frequency division duplexing (FDD),time division duplexing (TDD), or a combination of both.

In some examples, base station 105 or UE 115 may be equipped withmultiple antennas, which may be used to employ techniques such astransmit diversity, receive diversity, multiple-input multiple-output(MIMO) communications, or beamforming. For example, wirelesscommunications system 100 may use a transmission scheme between atransmitting device (e.g., a base station 105) and a receiving device(e.g., a UE 115), where the transmitting device is equipped withmultiple antennas and the receiving device is equipped with one or moreantennas. MIMO communications may employ multipath signal propagation toincrease the spectral efficiency by transmitting or receiving multiplesignals via different spatial layers, which may be referred to asspatial multiplexing. The multiple signals may, for example, betransmitted by the transmitting device via different antennas ordifferent combinations of antennas. Likewise, the multiple signals maybe received by the receiving device via different antennas or differentcombinations of antennas. Each of the multiple signals may be referredto as a separate spatial stream, and may carry bits associated with thesame data stream (e.g., the same codeword) or different data streams.Different spatial layers may be associated with different antenna portsused for channel measurement and reporting. MIMO techniques includesingle-user MIMO (SU-MIMO) where multiple spatial layers are transmittedto the same receiving device, and multiple-user MIMO (MU-MIMO) wheremultiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering,directional transmission, or directional reception, is a signalprocessing technique that may be used at a transmitting device or areceiving device (e.g., a base station 105 or a UE 115) to shape orsteer an antenna beam (e.g., a transmit beam or receive beam) along aspatial path between the transmitting device and the receiving device.Beamforming may be achieved by combining the signals communicated viaantenna elements of an antenna array such that signals propagating atparticular orientations with respect to an antenna array experienceconstructive interference while others experience destructiveinterference. The adjustment of signals communicated via the antennaelements may include a transmitting device or a receiving deviceapplying certain amplitude and phase offsets to signals carried via eachof the antenna elements associated with the device. The adjustmentsassociated with each of the antenna elements may be defined by abeamforming weight set associated with a particular orientation (e.g.,with respect to the antenna array of the transmitting device orreceiving device, or with respect to some other orientation).

In one example, a base station 105 may use multiple antennas or antennaarrays to conduct beamforming operations for directional communicationswith a UE 115. For instance, some signals (e.g. synchronization signals,reference signals, beam selection signals, or other control signals) maybe transmitted by a base station 105 multiple times in differentdirections, which may include a signal being transmitted according todifferent beamforming weight sets associated with different directionsof transmission. Transmissions in different beam directions may be usedto identify (e.g., by the base station 105 or a receiving device, suchas a UE 115) a beam direction for subsequent transmission and/orreception by the base station 105.

Some signals, such as data signals associated with a particularreceiving device, may be transmitted by a base station 105 in a singlebeam direction (e.g., a direction associated with the receiving device,such as a UE 115). In some examples, the beam direction associated withtransmissions along a single beam direction may be determined based atleast in in part on a signal that was transmitted in different beamdirections. For example, a UE 115 may receive one or more of the signalstransmitted by the base station 105 in different directions, and the UE115 may report to the base station 105 an indication of the signal itreceived with a highest signal quality, or an otherwise acceptablesignal quality. Although these techniques are described with referenceto signals transmitted in one or more directions by a base station 105,a UE 115 may employ similar techniques for transmitting signals multipletimes in different directions (e.g., for identifying a beam directionfor subsequent transmission or reception by the UE 115), or transmittinga signal in a single direction (e.g., for transmitting data to areceiving device).

A receiving device (e.g., a UE 115, which may be an example of a mmWreceiving device) may try multiple receive beams when receiving varioussignals from the base station 105, such as synchronization signals,reference signals, beam selection signals, or other control signals. Forexample, a receiving device may try multiple receive directions byreceiving via different antenna subarrays, by processing receivedsignals according to different antenna subarrays, by receiving accordingto different receive beamforming weight sets applied to signals receivedat a plurality of antenna elements of an antenna array, or by processingreceived signals according to different receive beamforming weight setsapplied to signals received at a plurality of antenna elements of anantenna array, any of which may be referred to as “listening” accordingto different receive beams or receive directions. In some examples areceiving device may use a single receive beam to receive along a singlebeam direction (e.g., when receiving a data signal). The single receivebeam may be aligned in a beam direction determined based at least inpart on listening according to different receive beam directions (e.g.,a beam direction determined to have a highest signal strength, highestsignal-to-noise ratio, or otherwise acceptable signal quality based atleast in part on listening according to multiple beam directions).

In certain implementations, the antennas of a base station 105 or UE 115may be located within one or more antenna arrays, which may support MIMOoperations, or transmit or receive beamforming. For example, one or morebase station antennas or antenna arrays may be co-located at an antennaassembly, such as an antenna tower. In some cases, antennas or antennaarrays associated with a base station 105 may be located in diversegeographic locations. A base station 105 may have an antenna array witha number of rows and columns of antenna ports that the base station 105may use to support beamforming of communications with a UE 115.Likewise, a UE 115 may have one or more antenna arrays that may supportvarious MIMO or beamforming operations.

In additional cases, UEs 115 and base stations 105 may supportretransmissions of data to increase the likelihood that data is receivedsuccessfully. HARQ feedback is one technique of increasing thelikelihood that data is received correctly over a communication link125. HARQ may include a combination of error detection (e.g., using acyclic redundancy check (CRC)), forward error correction (FEC), andretransmission (e.g., automatic repeat request (ARQ)). HARQ may improvethroughput at the MAC layer in poor radio conditions (e.g.,signal-to-noise conditions). In some cases, a wireless device maysupport same-slot HARQ feedback, where the device may provide HARQfeedback in a specific slot for data received in a previous symbol inthe slot, while in other cases, the device may provide HARQ feedback ina subsequent slot, or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basictime unit, which may, for example, refer to a sampling period ofT_(s)=1/30,720,000 seconds. Time intervals of a communications resourcemay be organized according to radio frames each having a duration of 10milliseconds (ms), where the frame period may be expressed asT_(f)=307,200 T_(s). The radio frames may be identified by a systemframe number (SFN) ranging from 0 to 1023. Each frame may include 10subframes numbered from 0 to 9, and each subframe may have a duration of1 ms. A subframe may be further divided into 2 slots each having aduration of 0.5 ms, and each slot may contain 6 or 7 modulation symbolperiods (e.g., depending on the length of the cyclic prefix prepended toeach symbol period). Excluding the cyclic prefix, each symbol period maycontain 2048 sampling periods. In some cases, a subframe may be thesmallest scheduling unit of the wireless communications system 100, andmay be referred to as a transmission time interval (TTI). In othercases, a smallest scheduling unit of the wireless communications system100 may be shorter than a subframe or may be dynamically selected (e.g.,in bursts of shortened TTIs (sTTIs) or in selected component carriersusing sTTIs).

In some wireless communications systems, a slot may further be dividedinto multiple mini-slots containing one or more symbols. In someinstances, a symbol of a mini-slot or a mini-slot may be the smallestunit of scheduling. Each symbol may vary in duration depending on thesubcarrier spacing or frequency band of operation, for example. Further,some wireless communications systems may implement slot aggregation inwhich multiple slots or mini-slots are aggregated together and used forcommunication between a UE 115 and a base station 105.

The term “carrier,” as may be used herein, refers to a set of radiofrequency spectrum resources having a defined physical layer structurefor supporting communications over a communication link 125. Forexample, a carrier of a communication link 125 may include a portion ofa radio frequency spectrum band that is operated according to physicallayer channels for a given radio access technology. Each physical layerchannel may carry user data, control information, or other signaling. Acarrier may be associated with a pre-defined frequency channel (e.g., anevolved universal mobile telecommunication system terrestrial radioaccess (E-UTRA) absolute radio frequency channel number (EARFCN)), andmay be positioned according to a channel raster for discovery by UEs115. Carriers may be downlink or uplink (e.g., in an FDD mode), or beconfigured to carry downlink and uplink communications (e.g., in a TDDmode). In some examples, signal waveforms transmitted over a carrier maybe made up of multiple sub-carriers (e.g., using multi-carriermodulation (MCM) techniques such as orthogonal frequency divisionmultiplexing (OFDM) or discrete Fourier transform spread OFDM(DFT-S-OFDM)).

The organizational structure of the carriers may be different fordifferent radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR).For example, communications over a carrier may be organized according toTTIs or slots, each of which may include user data as well as controlinformation or signaling to support decoding the user data. A carriermay also include dedicated acquisition signaling (e.g., synchronizationsignals or system information, etc.) and control signaling thatcoordinates operation for the carrier. In some examples (e.g., in acarrier aggregation configuration), a carrier may also have acquisitionsignaling or control signaling that coordinates operations for othercarriers.

Physical channels may be multiplexed on a carrier according to varioustechniques. A physical control channel and a physical data channel maybe multiplexed on a downlink carrier, for example, using time divisionmultiplexing (TDM) techniques, frequency division multiplexing (FDM)techniques, or hybrid TDM-FDM techniques. In some examples, controlinformation transmitted in a physical control channel may be distributedbetween different control regions in a cascaded manner (e.g., between acommon control region or common search space and one or more UE-specificcontrol regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radiofrequency spectrum, and in some examples the carrier bandwidth may bereferred to as a “system bandwidth” of the carrier or the wirelesscommunications system 100. For example, the carrier bandwidth may be oneof a number of predetermined bandwidths for carriers of a particularradio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). Insome examples, each served UE 115 may be configured for operating overportions or all of the carrier bandwidth. In other examples, some UEs115 may be configured for operation using a narrowband protocol typethat is associated with a predefined portion or range (e.g., set ofsubcarriers or RBs) within a carrier (e.g., “in-band” deployment of anarrowband protocol type).

In a system employing MCM techniques, a resource element may consist ofone symbol period (e.g., a duration of one modulation symbol) and onesubcarrier, where the symbol period and subcarrier spacing are inverselyrelated. The number of bits carried by each resource element may dependon the modulation scheme (e.g., the order of the modulation scheme).Thus, the more resource elements that a UE 115 receives and the higherthe order of the modulation scheme, the higher the data rate may be forthe UE 115. In MIMO systems, a wireless communications resource mayrefer to a combination of a radio frequency spectrum resource, a timeresource, and a spatial resource (e.g., spatial layers), and the use ofmultiple spatial layers may further increase the data rate forcommunications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations105 or UEs 115) may have a hardware configuration that supportscommunications over a particular carrier bandwidth, or may beconfigurable to support communications over one of a set of carrierbandwidths. In some examples, the wireless communications system 100 mayinclude base stations 105 and/or UEs 115 that support simultaneouscommunications via carriers associated with more than one differentcarrier bandwidth.

Wireless communications system 100 may support communication with a UE115 on multiple cells or carriers, a feature which may be referred to ascarrier aggregation or multi-carrier operation. A UE 115 may beconfigured with multiple downlink component carriers and one or moreuplink component carriers according to a carrier aggregationconfiguration. Carrier aggregation may be used with both FDD and TDDcomponent carriers.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers (eCCs). An eCC may be characterized by one or morefeatures including wider carrier or frequency channel bandwidth, shortersymbol duration, shorter TTI duration, or modified control channelconfiguration. In certain instances, an eCC may be associated with acarrier aggregation configuration or a dual connectivity configuration(e.g., when multiple serving cells have a suboptimal or non-idealbackhaul link). An eCC may also be configured for use in unlicensedspectrum or shared spectrum (e.g., where more than one operator isallowed to use the spectrum, such as NR-shared spectrum (NR-SS)). An eCCcharacterized by wide carrier bandwidth may include one or more segmentsthat may be utilized by UEs 115 that are not capable of monitoring thewhole carrier bandwidth or are otherwise configured to use a limitedcarrier bandwidth (e.g., to conserve power).

In additional cases, an eCC may utilize a different symbol duration thanother component carriers, which may include use of a reduced symbolduration as compared with symbol durations of the other componentcarriers. A shorter symbol duration may be associated with increasedspacing between adjacent subcarriers. A device, such as a UE 115 or basestation 105, utilizing eCCs may transmit wideband signals (e.g.,according to frequency channel or carrier bandwidths of 20, 40, 60, 80MHz, etc.) at reduced symbol durations (e.g., 16.67 microseconds). A TTIin eCC may consist of one or multiple symbol periods. In some cases, theTTI duration (that is, the number of symbol periods in a TTI) may bevariable.

Wireless communications system 100 may be an NR system that may utilizeany combination of licensed, shared, and unlicensed spectrum bands,among others. The flexibility of eCC symbol duration and subcarrierspacing may allow for the use of eCC across multiple spectrums. In someexamples, NR shared spectrum may increase spectrum utilization andspectral efficiency, specifically through dynamic vertical (e.g., acrossthe frequency domain) and horizontal (e.g., across the time domain)sharing of resources.

FIG. 2 shows a block diagram of a design of a base station 105 and a UE115, which may be one of the base station and one of the UEs in FIG. 1.At base station 105, a transmit processor 220 may receive data from adata source 212 and control information from a controller/processor 240.The control information may be for the PBCH, PCFICH, PHICH, PDCCH,EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmitprocessor 220 may process (e.g., encode and symbol map) the data andcontrol information to obtain data symbols and control symbols,respectively. The transmit processor 220 may also generate referencesymbols, e.g., for the PSS, SSS, and cell-specific reference signal. Atransmit (TX) multiple-input multiple-output (MIMO) processor 230 mayperform spatial processing (e.g., precoding) on the data symbols, thecontrol symbols, and/or the reference symbols, if applicable, and mayprovide output symbol streams to the modulators (MODs) 232 a through 232t. Each modulator 232 may process a respective output symbol stream(e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator232 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal.Downlink signals from modulators 232 a through 232 t may be transmittedvia the antennas 234 a through 234 t, respectively.

At UE 115, the antennas 252 a through 252 r may receive the downlinksignals from the base station 105 and may provide received signals tothe demodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 254 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all the demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 115 to a data sink 260, and provide decoded control informationto a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive andprocess data (e.g., for the PUSCH) from a data source 262 and controlinformation (e.g., for the PUCCH) from the controller/processor 280. Thetransmit processor 264 may also generate reference symbols for areference signal. The symbols from the transmit processor 264 may beprecoded by a TX MIMO processor 266 if applicable, further processed bythe modulators 254 a through 254 r (e.g., for SC-FDM, etc.), andtransmitted to the base station 105. At the base station 105, the uplinksignals from the UE 115 may be received by the antennas 234, processedby the demodulators 232, detected by a MIMO detector 236 if applicable,and further processed by a receive processor 238 to obtain decoded dataand control information sent by the UE 115. The processor 238 mayprovide the decoded data to a data sink 239 and the decoded controlinformation to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at thebase station 105 and the UE 115, respectively. The controller/processor240 and/or other processors and modules at the base station 105 mayperform or direct the execution of various processes for the techniquesdescribed herein. The controllers/processor 280 and/or other processorsand modules at the UE 115 may also perform or direct the execution ofthe functional blocks illustrated in FIGS. 4A and 4B, and/or otherprocesses for the techniques described herein. The memories 242 and 282may store data and program codes for the base station 105 and the UE115, respectively. A scheduler 244 may schedule UEs for datatransmission on the downlink and/or uplink.

As wireless technologies advance, mobile network operator (MNO)-drivenwide-area networks will continue servicing traditional use cases. 5Gtechnology is expected to expand beyond traditional use cases to newapplications in healthcare, industrial internet-of-things (HOT), etc.Certain non-traditional use case scenarios may benefit from solutions tocurrent issues in order to meet the stringent need of ultra-reliable,low latency communication (URLLC) services. In a mission critical (MiCr)application, URLLC operations may expect a 10⁻⁶ packet error rate, mslatency, all in multi-year 24 hour, 7 days per week (24/7) operation.Extending into NR features, 5G NR-U will have support for both licenseassisted access (LAA), in which unlicensed channels are assisted bylicensed channels for guaranteed communications, and standalone mode.

Spectrum availability continues to be at the forefront of discussionsfor increasing wireless service access. One target for NR-U deploymentshas been suggested for the 5 GHz band and the upcoming 6 GHz band.However, the existing medium access procedure in the unlicensed 5 GHzband can create a number of issues that may result in poor performance,thus, making unlicensed spectrum difficult for such new high priorityapplications. The 5 GHz band, which may be shared with other radioaccess technologies, such as WiFi, may suffer interference caused byhidden and exposed nodes, loose quality of service (QoS) control, andinadequate support for new advanced transmission techniques, such asCoMP, etc. In fact, any frequency band accessible for NR-U operationsmay include various radio access technologies contending forcommunications access.

In responding to demands for more “mid-band” unlicensed spectrum tosupplement the unlicensed spectrum already available in the 5 GHz band,consideration has been made by governmental authorities to open the 6GHz band (e.g., 5.925-7.125 GHz) for unlicensed use. The 6 GHz band iscurrently used by licensed incumbents, such as fixed, mobile, andsatellite services. In order to open the 6 GHz band, sophisticatedsharing mechanisms will be used to protect these licensed incumbents.Because the 6 GHz band has not been open to unlicensed use, it does nothave “legacy” secondary users or radio access technologies alsocontending for communications access. As such, it may offeropportunities to develop new procedures that may support these newuse-cases in an unlicensed spectrum. Various aspects of the presentdisclosure are directed to providing enhanced mechanisms for handlingtechnology neutral medium access that may allow for advanced uses ofunlicensed spectrum.

As may be readily understood, multiple nodes may be situated in such amanner that provides the coverage areas of each node to substantiallyoverlap with the coverage area of the other nodes. Some of the nodes mayhave portions of their respective coverage area that are not overlappedby the other nodes. However, the coverage area of certain of these nodesmay be completely overlapped by either or all of the coverage areas ofthe other nodes. In providing communications with UEs connected to thesenodes, the medium access procedure for each node would include acontention window, in which each node contends for the sharedcommunication channel. However, while scenarios exist where the nodesthat have some non-overlapped coverage area may have a successfulcontention procedure to secure channel occupancy times (COTs) forcommunications, because none of the contention windows for each of thenodes overlaps, the node with all of its coverage area overlapped maynot have an opportunity to access the medium as long as the other nodesare not within the sensing range of each other and are using the medium.

With current medium access rules, existing listen before talk (LBT)schemes may suffer from starvation (e.g., failure to secure channelaccess) due to interference experienced from exposed or hidden nodes.The medium access procedure is further not well defined for CoMPoperations. Trigger-based schemes used for uplink multi-user multipleinput, multiple output (MU-MIMO) operations may not be considered “fair”due to the potentially higher transmit power of the access pointscompared to its clients. Additionally, there is no current or practicaltechnology neutral way to protect the receiver. When defined in WiFioperations, receiver protection techniques have not perform well inheavily loaded scenarios when WiFi preambles are not detected due to lowsignal-to-interference plus noise ratio (SINR).

Synchronous access schemes have been suggested for such unlicensed mediato improve handling of these access issues. Synchronization can improvefairness since it enables overlapping contention windows. Each nodewould theoretically get fair share of the medium. In addition, it mayhelp mitigate hidden node interference issues, since, at a given time,all nodes would monitor control signaling. Moreover, receiverprotection, analogous to clear-to-send (CTS) message is possible toachieve in a technology neutral way.

FIG. 3 is a block diagram illustrating a portion of NR-U network 30configured to support synchronous communication mode within a sharedcommunication spectrum. As illustrated, three wireless nodes, nodes 1-3,have been situated such that the coverage areas of each nodesubstantially overlaps with the coverage area of the other nodes. Nodes1 and 3 may have portions of its coverage area that are not overlappedby the other nodes, respectively. However, the coverage area of node 2is completely overlapped by either the coverage area of node 1 or node3. FIG. 3 further shows the illustrative timelines for each of nodes1-3. In providing communications with UEs 115 a-c, the medium accessprocedure for each node includes contention windows in which each nodemay contend for the shared communication channel. However, withoutability to implement synchronous communication modes, while scenariosexist where node 1 and 3 may have a successful contention procedure tosecure channel occupancy times (COTs) for communications, because noneof the contention windows for each of nodes 1-3 overlaps, node 2 willnot have an opportunity to access the medium as long as nodes 1 and 3are not within the sensing range of each other and are using the medium.

Within an unlicensed spectrum band, various devices and radio accesstechnologies could elect to contend for communications usingasynchronous or synchronous communication modes. As illustrated, asynchronous communications mode is configured by setting synchronizationboundaries 300-304 for each of the participating nodes. Technologieshave been suggested to encourage contending devices to elect synchronouscommunication modes over asynchronous modes. For example, nodes 1-3, asconforming to the synchronous communication mode, may be allowed toextend its COT beyond the nominal value, so as to end at thesynchronization boundary, that may either be defined globally orlocally. For example, at synchronization boundary 300, node 3 performscontention 305 and sets COT 306. However, due to limited data fortransmission, node 3 ends the transmission of COT 306 at 307, thus,losing synchronization. Node 2 opportunistically performs contention 308to define COT 309 for transmission. Because node 2 has sufficient datain its buffer and has obtained COT 309 after synchronization boundary300, it may continue transmissions past synchronization boundary 301 andend at synchronization boundary 302.

At synchronization boundary 302, node 1 performs contention 310 anddefines COT 301 with limits data in its buffer. At 312, synchronizationis again lost, with node 2 opportunistically performing contention 313to define COT 314. As before, because node 2 is able to define COT 314after synchronization boundary 302, it may set the ending of COT 314 tothe next following boundary, past synchronization boundary 303 tosynchronization boundary 304, where node 2 again performs contention 315to define COT 316. Where the synchronization period, N, betweensynchronization boundaries 300-304 is set to 6 ms (N=6 ms), detecting asignificant fraction of channel occupancy (COT) end times at a periodicinterval equal to the synchronization period (N=6 ms) or an integermultiple thereof, can indicate the presence of synchronous communicationmode.

Synchronous communication mode operations can be detected by detectingthe periods between on/off transitions equal to an integer multiple ofthe synchronization period (e.g., N=6 ms, as provided in the exampleabove) on at least a certain fraction of the synchronization referenceboundaries. The probabilities for misdetection or false alarm may bedecreased by increasing the length of the observation period. However,increasing the observation period comes with a trade-off of increasingthe time of detection.

Moreover, use and configuration of a synchronous communication mode maybe defined either globally or locally. On a local basis, multiplecompatible nodes may coordinate to conduct synchronous modecommunications in a particular area of the network. In such case, thesynchronization period may be configured locally between theparticipating node. On a global basis, a network may configurecommunications for a particular area to be conducted in a synchronousmode. Therefore, there could be instances where both a globalsynchronous communication mode and local synchronous communication modeare present in the same location. In such example instances, a means fordifferentiating between the global and local synchronous operation maybe desirable, as the global synchronous operation would likely havepriority over the local mode. As contending communications over theshared spectrum occurs between various radio access technologies, atechnology neutral way to indicate the global synchronous mode may bebeneficial.

FIG. 4A is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure. The example blocks willalso be described with respect to base station 105, as illustrated inFIGS. 2 and 6, operating as a node. FIG. 6 is a block diagramillustrating base station 105 configured according to one aspect of thepresent disclosure. Base station 105 includes the structure, hardware,and components as illustrated for base station 105 of FIG. 2. Forexample, base station 105 includes controller/processor 240, whichoperates to execute logic or computer instructions stored in memory 242,as well as controlling the components of base station 105 that providethe features and functionality of base station 105. Base station 105,under control of controller/processor 240, transmits and receivessignals via wireless radios 600 a-t and antennas 234 a-t. Wirelessradios 600 a-t includes various components and hardware, as illustratedin FIG. 2 for base station 105, including modulator/demodulators 232a-t, MIMO detector 236, receive processor 238, transmit processor 220,and TX MIMO processor 230.

The example blocks will also be described with respect to UE 115, asillustrated in FIGS. 2 and 7, operating as a node. FIG. 7 is a blockdiagram illustrating UE 115 configured according to one aspect of thepresent disclosure. UE 115 includes the structure, hardware, andcomponents as illustrated for UE 115 of FIG. 2. For example, UE 115includes controller/processor 280, which operates to execute logic orcomputer instructions stored in memory 282, as well as controlling thecomponents of UE 115 that provide the features and functionality of UE115. UE 115, under control of controller/processor 280, transmits andreceives signals via wireless radios 700 a-r and antennas 252 a-r.Wireless radios 700 a-r includes various components and hardware, asillustrated in FIG. 2 for UE 115, including modulator/demodulators 254a-r, MIMO detector 256, receive processor 258, transmit processor 264,and TX MIMO processor 266.

At block 400, a first node contends for access to a shared communicationspectrum with an LBT procedure at a synchronization boundary. When abase station, such as base station 105, operates as a node according tothe aspects of the present disclosure, base station 105 may attemptaccess to the shared spectrum by performing an LBT procedure. Undercontrol of controller/processor 240, base station 105 executes LBT logic604. The execution of the instructions and controls of LBT logic 604(referred to as “the execution environment”) provide the functionalityfor base station 105 to perform LBT procedures for access to the sharedspectrum. As noted above, LBT procedures may include various operationsto determine whether other contending signals are occupying the sharedspectrum (e.g., CCA checks, Cat. 1-4 LBT procedures, etc.). Within theexecution environment of LBT logic 604, base station 105 may attempt toestablish a COT with a successful LBT procedure. Base station 105monitors for signals occupying the shared communication spectrum viasignals received through antennas 234 a-t and wireless radios 600 a-t.

When a UE, such as UE 115, operates as a node according to the aspectsof the present disclosure, UE 115 may attempt access to the sharedspectrum also by performing an LBT procedure. Under control ofcontroller/processor 280, UE 115 executes LBT logic 704. Within theexecution environment of LBT logic 704, UE 115 may attempt to establisha COT with a successful LBT procedure. UE 115 monitors for signalsoccupying the shared communication spectrum via signals received throughantennas 252 a-r and wireless radios 700 a-r.

At block 401, the first node transmits according to a firstsynchronization mode, data in a COT established in response to successof the LBT procedure. Base station 105, when operating as the node, usescommunication configuration information stored at synchronizationconfiguration 602, in memory 242, to conduct communications according toa synchronization mode. The synchronization mode may be a globalsynchronization mode, defined by the network for use across the networkor a portion of the network, or a local synchronization mode, defined bycoordinating nodes with synchronization capabilities. When the LBTprocedure is successful, thus, establishing a COT for transmission bybase station 105, base station 105 would transmit data during theestablished COT via wireless radios 600 a-t and antennas 234 a-t.

UE 115, when operating as the node, uses communication configurationinformation stored at synchronization configuration 702, in memory 282,to conduct communications according to a synchronization mode. Thesynchronization mode may be a global synchronization mode, defined bythe network for use across the network or a portion of the network, or alocal synchronization mode, defined by coordinating nodes withsynchronization capabilities. When the LBT procedure is successful,thus, establishing a COT for transmission by UE 115, UE 115 wouldtransmit data during the established COT via wireless radios 700 a-r andantennas 252 a-r.

At block 402, the first node transmits an indication signal after an endof the COT at a subsequent synchronization boundary, wherein theindication signal identifies the first synchronization mode. Basestation 105, when operating as the node, identifies the synchronizationmode used within the execution environment of synchronizationconfiguration 602. Based on the synchronization mode used, base station105 selects the associated indication signal pattern from indicationsignal configuration 603. Base station 105 may then, under control ofcontroller/processor 240, transmit the associated pattern for theindication signal after the end of transmissions at the synchronizationboundary via wireless radios 600 a-t and antennas 234 a-t. The selectedpattern for the indication signal uniquely identifies thesynchronization mode used in the transmissions of base station 105.

UE 115, when operating as the node, identifies the synchronization modeused within the execution environment of synchronization configuration702. Based on the synchronization mode used, UE 115 selects theassociated indication signal pattern from indication signalconfiguration 703. UE 115 may then, under control ofcontroller/processor 280, transmit the associated pattern for theindication signal after the end of transmissions at the synchronizationboundary via wireless radios 700 a-r and antennas 252 a-r. The selectedpattern for the indication signal uniquely identifies thesynchronization mode used in the transmissions of UE 115.

FIG. 4B is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure. The example blocks ofFIG. 4B will also be described with respect to base station 105 and UE115, as illustrated in FIGS. 2, 6, and 7, operating as a node.

At block 410, a first node detects an indication signal transmitted by asecond node at a synchronization boundary of a shared communicationchannel, wherein the indication signal identifies a first transmissionsynchronization mode of the second node. A base station, such as basestation 105, when operating as a node contending for access to sharedcommunication spectrum where both synchronous and asynchronouscommunications are allowed, base station 105, under control ofcontroller/processor 240, executes synchronization detection logic 601.The execution environment of synchronization detection logic 601provides the features and functionality for base station 105 to detectwhether synchronous communication modes are being used in the sharedcommunication spectrum to which base station 105 contends for access.Within the execution environment of synchronization detection logic 601,base station 105 monitors for an indication signal after synchronizationboundaries. Base station 105 monitors for signals occupying the sharedcommunication spectrum via signals received through antennas 234 a-t andwireless radios 600 a-t. When detected, base station 105 may compare theoff-on pattern of the indication signal against the multiple patternsstored at indication signal configuration 603, in memory 242. Basestation 105 may then identify which type of synchronous communicationmode is being used in the communications on the shared communicationchannel.

UE 115, when operating as the node contending for access to sharedcommunication spectrum where both synchronous and asynchronouscommunications are allowed, UE 115, under control ofcontroller/processor 280, executes synchronization detection logic 701.The execution environment of synchronization detection logic 701provides the features and functionality for UE 115 to detect whethersynchronous communication modes are being used in the sharedcommunication spectrum to which UE 115 contends for access. Within theexecution environment of synchronization detection logic 701, UE 115monitors for an indication signal after synchronization boundaries. UE115 monitors for signals occupying the shared communication spectrum viasignals received through antennas 252 a-r and wireless radios 700 a-r.When detected, UE 115 may compare the off-on pattern of the indicationsignal against the multiple patterns stored at indication signalconfiguration 703, in memory 282. UE 115 may then identify which type ofsynchronous communication mode is being used in the communications onthe shared communication channel.

At block 411, the first node adjusts a communications configuration forthe shared communication channel in response to detection of theindication signal. A base station, such as base station 105, whenoperating as a node contending for access to the shared communicationspectrum, within the execution environment of synchronization detectionlogic, uses the identified synchronous communication mode to performadjustments to its communication configuration. The adjustment can beeither base station 105 contending for communications on the sharedcommunication channel using the first transmission synchronization modeor in refraining from attempting the communications on the sharedcommunication channel using a second transmission synchronization mode.In one example implementation, upon detection of a globalsynchronization mode via the indication signal, other nodes, such asbase station 105, may, at least for some predetermined duration of timeand/or as long as the nodes continue to detect the indication signalidentifying the global synchronization mode, either follow the globalsynchronization mode for communications or refrain from using a localsync mode, and/or if there is sufficient data in the buffer (not shown),to adjust their COT so that it ends at the synchronization boundary. Forthe presently-described example implementation, it may be assumed thatthe indication signal, if any, plus the contention time, plus the COT isequal to the synchronization period (N=6 ms).

UE 115, when operating as a node contending for access to the sharedcommunication spectrum, within the execution environment ofsynchronization detection logic, uses the identified synchronouscommunication mode to perform adjustments to its communicationconfiguration. The adjustment can be either UE 115 contending forcommunications on the shared communication channel using the firsttransmission synchronization mode or in refraining from attempting thecommunications on the shared communication channel using a secondtransmission synchronization mode. In one example implementation, upondetection of a global synchronization mode via the indication signal,other nodes, such as UE 115, may, at least for some predeterminedduration of time and/or as long as the nodes continue to detect theindication signal identifying the global synchronization mode, eitherfollow the global synchronization mode for communications or refrainfrom using a local sync mode, and/or if there is sufficient data in thebuffer (not shown), to adjust their COT so that it ends at thesynchronization boundary.

FIGS. 5A and 5B are block diagrams illustrating portions of NR-U network50 and 51 having nodes 1-3 serving UEs 115 a-115 c, in which all suchnodes are configured for indicating synchronous communications accordingto aspects of the present disclosure. As illustrated in FIGS. 5A and 5B,three wireless nodes, nodes 1-3, have been situated such that thecoverage areas of each node substantially overlaps with the coveragearea of the other nodes. Nodes 1 and 3 may have portions of its coveragearea that are not overlapped by the other nodes, respectively. However,the coverage area of node 2 is completely overlapped by either thecoverage area of node 1 or node 3. FIGS. 5A and 5B further show theillustrative timelines for each of nodes 1-3. A synchronouscommunication mode may be implemented through configuration ofsynchronization boundaries 500-502 occurring at a synchronizationperiod, N. The illustrated aspects may provide for the synchronouscommunication mode to be globally defined or locally defined in whichthe indication signal identifies the synchronization mode as that ofbeing either global or local.

In the example aspect of FIG. 5A, nodes 1-3 are configured to provide anindication signal that identifies a synchronization mode according to anaspect of the present disclosure. For example, node 2 ends a synchronousmode transmission, COT 503, at synchronization boundary 500. Accordingto the various aspects, node 2 is configured to then transmit theindication signal 504 at synchronization boundary 500. In theillustrated aspect, indication signal 504 includes a unique off/onpattern. As noted above, the pattern may begin with a single “off” slot,which would ensure that synchronous mode detection is not significantlyimpacted and the countdown of the LBT procedure is not triggered.Because nodes 1 and 3 are also contending for access to the sharedcommunication channel of NR-U network 50, the pattern should beconfigured in order not to impact LBT procedure.

In a first example implementation, node 2 is operating in a globalsynchronization mode. Thus, indication signal 504 identifies that NR-Unetwork 50 is currently operating under a global synchronization mode.Nodes 1 and 3 may detect indication signal 504 and adjust theircommunications configuration accordingly. For example, node 1 may alsobe configured with global synchronization mode capability. When itdetects indication of a global synchronization mode, it may beconfigured to also operate in global synchronization mode, either for apredetermined duration or until node 1 no longer detects the indicationof the global synchronization mode. Thus, after detecting indicationsignal 507 at synchronization boundary 501 following contention 505 andtransmissions in COT 506 by node 2, node 1 opportunistically securesaccess to the shared spectrum with contention 508 followed bytransmissions during COT 509. After completing its transmissions in COT509 at synchronization boundary 502, node 1 is further configured totransmit indication signal 510. Indication signal 510 has the sameunique pattern that identifies the global synchronization modeoperation. After detecting indication signal 510, node 2 may reclaimaccess to the shared spectrum using contention 511 to secure COT 512 foradditional transmissions using the global synchronization mode.

Additionally, node 3 may be configured for local synchronization mode.Therefore, once node 3 detects indication signal 504, its configurationprovides that it is to refrain from using the local synchronizationmode, either for a predetermined duration or until node 3 no longerdetects the indication of the global synchronization mode. Node 3 doesnot attempt to access NR-U 50 using the local synchronization mode forthe predetermined duration.

It should be noted that in an alternative aspect of the presentdisclosure, node 2 is operating in a local synchronization mode.According to the alternative aspect, nodes operating in the localsynchronization mode are configured to transmit the indication signalthat identifies the local synchronization mode. In such alternativeaspect, nodes that detect this indication signal would either conductall communications using the local synchronization mode or refrain fromusing the global synchronization mode for transmissions, in both caseseither for a predetermined duration or until the node no longer detectsthe indication signal.

In the example aspect of FIG. 5B, instead of node 1 operating in aglobal synchronization mode, it operates in a local synchronizationmode. As node 1 monitors the shared spectrum of NR-U network 51 anddetects indication signals 504 and 507, it understands that globalsynchronization mode communications are occurring. However, when it canopportunistically contend for access to the shared communicationspectrum after detecting indication signal 507 at synchronizationboundary 501, it secures COT 509 using contention 508 and beginstransmission. After ending its transmission in COT 509 atsynchronization boundary 502, it has been configured to signal adifferent indicator. After ending COT 509 and synchronization boundary502, node 1 transmits indication signal 520. Indication signal 520 isformed using a different off-on pattern than indication signals 504 and507, which indicate a global synchronization mode. The pattern ofindication signal 520, instead, indicates a local synchronization modeoperation. Thus, in detecting indication signal 520, nodes 2 and 3 maydetermine that local synchronization mode communications are alsooccurring in the shared communication spectrum of NR-U network 51.

It should be noted that, as indicated above, in an alternative aspect,node 2 may be operating in the local synchronization mode and node 1operates in the global synchronization mode, where indication signals504 and 507 indicate the local synchronization mode and indicationsignal 520 indicates the global synchronization mode.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

The functional blocks and modules in FIGS. 4A and 4B may compriseprocessors, electronics devices, hardware devices, electronicscomponents, logical circuits, memories, software codes, firmware codes,etc., or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure. Skilled artisans will also readilyrecognize that the order or combination of components, methods, orinteractions that are described herein are merely examples and that thecomponents, methods, or interactions of the various aspects of thepresent disclosure may be combined or performed in ways other than thoseillustrated and described herein.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another.Computer-readable storage media may be any available media that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, such computer-readable media can compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to carry or store desired program code means in the form ofinstructions or data structures and that can be accessed by ageneral-purpose or special-purpose computer, or a general-purpose orspecial-purpose processor. Also, a connection may be properly termed acomputer-readable medium. For example, if the software is transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, or digital subscriber line (DSL), thenthe coaxial cable, fiber optic cable, twisted pair, or DSL, are includedin the definition of medium. Disk and disc, as used herein, includescompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk and blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

As used herein, including in the claims, the term “and/or,” when used ina list of two or more items, means that any one of the listed items canbe employed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination. Also, as usedherein, including in the claims, “or” as used in a list of itemsprefaced by “at least one of” indicates a disjunctive list such that,for example, a list of “at least one of A, B, or C” means A or B or C orAB or AC or BC or ABC (i.e., A and B and C) or any of these in anycombination thereof.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of wireless communication, comprising:detecting, by a first node, an indication signal transmitted by a secondnode at a synchronization boundary of a shared communication channel,wherein the indication signal identifies a first transmissionsynchronization mode of the second node; adjusting, by the first node, acommunications configuration for the shared communication channel inresponse to detection of the indication signal, wherein an adjustment tothe communications configuration includes one of: contending, by thefirst node, for communications on the shared communication channel usingthe first transmission synchronization mode; or refraining, by the firstnode, from attempting the communications on the shared communicationchannel using a second transmission synchronization mode.
 2. The methodof claim 1, further including, in response to detection of theindication signal: adjusting, by the first node, a channel occupancytime (COT) to end at a next synchronization boundary, wherein theadjusting is in response to a threshold amount of data in a buffer ofthe first node.
 3. The method of claim 1, further including one of:transmitting, by the first node, the indication signal at a subsequentsynchronization boundary after completion of transmissions at thesubsequent synchronization boundary, wherein the transmitting theindication signal is in response to the first node configured for use ofthe first transmission synchronization mode; transmitting, by the firstnode, a second indication signal at the subsequent synchronizationboundary after completion of the transmissions at the subsequentsynchronization boundary, wherein the second indication signal isdifferent than the indication signal, and wherein the transmitting thesecond indication signal is in response to the first node configured foruse of a second transmission synchronization mode associated with thesecond indication signal; or refraining, by the first node, fromtransmission of the indication signal at the subsequent synchronizationboundary after completion of the transmissions at the subsequentsynchronization boundary, wherein the first node is configured to usethe second transmission synchronization mode.
 4. The method of claim 1,wherein the indication signal includes an off-on transmission pattern ofslots that begins with a single off slot.
 5. The method of claim 1,wherein one of the first transmission synchronization mode is a globalsynchronization mode and the second transmission synchronization mode isa local synchronization mode, or the first transmission synchronizationmode is the local synchronization mode and the second transmissionsynchronization mode is the global synchronization mode.
 6. The methodof claim 1, wherein the adjusting includes one of: adjusting thecommunications configuration for a predetermine period of time; oradjusting the communications configuration until the first node fails todetect the indication signal at a next consecutive synchronizationboundary.
 7. A method of wireless communication, comprising: contending,by a first node, for access to a shared communication spectrum with alisten before talk (LBT) procedure at a synchronization boundary;transmitting, by the first node, according to a first synchronizationmode, data in a channel occupation time (COT) established in response tosuccess of the LBT procedure; and transmitting, by the first node, anindication signal after an end of the COT at a subsequentsynchronization boundary, wherein the indication signal identifies thefirst synchronization mode.
 8. The method of claim 7, wherein theindication signal includes an off-on pattern uniquely associated withthe first synchronization mode and distinguishable from one or moreadditional off-on patterns uniquely associated with one or moreadditional synchronization modes.
 9. An apparatus configured forwireless communication, the apparatus comprising: at least oneprocessor; and a memory coupled to the at least one processor, whereinthe at least one processor is configured: to detect, by a first node, anindication signal transmitted by a second node at a synchronizationboundary of a shared communication channel, wherein the indicationsignal identifies a first transmission synchronization mode of thesecond node; to adjust, by the first node, a communicationsconfiguration for the shared communication channel in response todetection of the indication signal, wherein an adjustment to thecommunications configuration includes configuration of the at least oneprocessor to one of: contend, by the first node, for communications onthe shared communication channel using the first transmissionsynchronization mode; or refrain, by the first node, from attempting thecommunications on the shared communication channel using a secondtransmission synchronization mode.
 10. The apparatus of claim 9, furtherincluding configuration of the at least one processor, in response todetection of the indication signal: to adjust, by the first node, achannel occupancy time (COT) to end at a next synchronization boundary,wherein the configuration of the at least one processor to adjust isexecuted in response to a threshold amount of data in a buffer of thefirst node.
 11. The apparatus of claim 9, further includingconfiguration of the at least one processor to one of: transmit, by thefirst node, the indication signal at a subsequent synchronizationboundary after completion of transmissions at the subsequentsynchronization boundary, wherein the configuration of the at least oneprocessor to transmit the indication signal is executed in response tothe first node configured for use of the first transmissionsynchronization mode; transmit, by the first node, a second indicationsignal at the subsequent synchronization boundary after completion ofthe transmissions at the subsequent synchronization boundary, whereinthe second indication signal is different than the indication signal,and wherein the configuration of the at least one processor to transmitthe second indication signal is executed in response to the first nodeconfigured for use of a second transmission synchronization modeassociated with the second indication signal; or refrain, by the firstnode, from transmission of the indication signal at the subsequentsynchronization boundary after completion of the transmissions at thesubsequent synchronization boundary, wherein the first node isconfigured to use the second transmission synchronization mode.
 12. Theapparatus of claim 9, wherein the indication signal includes an off-ontransmission pattern of slots that begins with a single off slot. 13.The apparatus of claim 9, wherein one of the first transmissionsynchronization mode is a global synchronization mode and the secondtransmission synchronization mode is a local synchronization mode, orthe first transmission synchronization mode is the local synchronizationmode and the second transmission synchronization mode is the globalsynchronization mode.
 14. The apparatus of claim 9, wherein theconfiguration of the at least one processor to adjust includesconfiguration of the at least one processor to one of: adjust thecommunications configuration for a predetermine period of time; oradjust the communications configuration until the first node fails todetect the indication signal at a next consecutive synchronizationboundary.
 15. An apparatus configured for wireless communication, theapparatus comprising: at least one processor; and a memory coupled tothe at least one processor, wherein the at least one processor isconfigured: to contend, by a first node, for access to a sharedcommunication spectrum with a listen before talk (LBT) procedure at asynchronization boundary; to transmit, by the first node, according to afirst synchronization mode, data in a channel occupation time (COT)established in response to success of the LBT procedure; and totransmit, by the first node, an indication signal after an end of theCOT at a subsequent synchronization boundary, wherein the indicationsignal identifies the first synchronization mode.
 16. The apparatus ofclaim 15, wherein the indication signal includes an off-on patternuniquely associated with the first synchronization mode anddistinguishable from one or more additional off-on patterns uniquelyassociated with one or more additional synchronization modes.